A. Field of the Invention
The present invention relates generally to compositions that can be used to improve the skin's visual appearance. In certain aspects, the compositions of the present invention can include, for example, a combination of ingredients to whiten skin, even out skin color, or treat hyperpigmentation. This combination of ingredients can be included in a wide-range of product formulations (e.g., serums, eye creams, toners, gels, masks, etc.).
B. Description of Related Art
The color in human skin is caused by the pigment melanin. Melanin is produced in special dendritic cells, melanocytes, which are found below or between the basal cells of the epidermis of the skin (U.S. Pat. No. 5,411,741). When exposed to damaging environmental factors such the ultra violet (UV) radiation of the sun, irritants, and pollution, the keratinocyte (outermost cell of the skin) releases signaling molecules, such as α-melanocyte-stimulating hormone (α-MSH), and inflammatory cytokines. These hormones trigger melanocytes to produce melanin (Garcia-Borron et al., 2005).
Typical pigmentation is characterized by an even, uniform coloration of the skin. Many individuals have excess melanin pigmentation or a hyperpigmentation patch which can cause pigmentary variation or abnormal pigmentation of the skin. This may lead to unwanted freckles or dark spots such as senile lentigo, liver spots, melasma, brown or age spots, vitiligo, sunburn pigmentation, post-inflammatory hyperpigmentation due to abrasion, burns, wounds or dermatitis, phototoxic reaction and other similar small, fixed pigmented lesions. It is often desirable to lighten these areas or even out the appearance of irregularly pigmented areas of skin. Individuals may also wish to increase fairness or reduce the overall level of pigmentation in the skin. In either case, the hyperpigmentation is usually viewed as cosmetically undesirable and individuals often wish to lighten the skin.
In some instances, the use of one skin lightening ingredient may not be effective for individuals with significant hyperpigmentation, freckles, or age spots, for example. Additionally, previous attempts to combine various skin lightening ingredients have been ineffective, and in some instance, have produced negative results (Talwar 1993).